The order Tselfatiiformes comprises three families, the Protobramidae (three genera and four species), the Eoplethodidae (one genus and one species) and the Plethodidae (seventeen genera and twenty-seven species). Although very specialised, the Protobramidae are the most primitive family within the order. Eoplethodidae, only known by the caudal skeleton, are less evolved than the Plethodidae. Within the Plethodidae, Paranogmius, the only one keeping a subtemporal fossa, is the most plesiomorphic genus. A more apomorphic clade unites together Bananogmius, Niobrara, Syntegmodus and Luxilites. Another clade still more apomorphic joins Martinichthys, Pseudothryptodus, Thryptodus and Plethodus. Pseudanogmius, Pentanogmius, Zanclites and Bachea are successively more and more specialised genera. Enischnorhynchus, Tselfatia and Dixonanogmius, with their skull roof strongly curved in cross-section, represent the most advanced clade. Moorevillia, characterised by its latero-parietal skull, could not be classified unambiguously within the family. The relative positions of the Tselfatiiformes and the Pachyrhizodontoidei within the Clupeocephala are discussed. The latter are considered to be more primitive than the former. The paleozoogeography of the Tselfatiiformes is also considered. They appear in the Eurafrican Mesogea during the Albian and expand there during the Cenomanian and Turonian. During the same period, they get across the Proto-Atlantic Ocean and colonize the north of South America, the Gulf of Mexico, Central America and the North American seaway. During the Coniacian and Santonian, they are abundant in North America but seem to be absent from the Eurafrican Mesogea. A few species subsist in the Gulf of Mexico and in Egypt during the Campanian. The Tselfatiiformes disappear after the Campanian.
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